In magnetic tape recording applications, such as computer data storage, data are recorded on or read from one or more parallel tracks positioned on a magnetic tape. For reading and writing, the tape is moved at constant speed past one or more magnetic tape heads. In order to ensure unambiguous readings and recordings, it is necessary to establish and maintain a fixed orientation of the tape head with respect to the moving tape. A standard orientation maintains the tape head centered transversely on the track passing it and the record gap therein at a ninety-degree angle relative to the direction of tape travel. Centering the head crosswise of the track is known as vertical or transverse alignment. Angular positioning is known as skew or azimuth alignment
Conventionally skew and vertical alignment are checked by means of separate test tapes having alternating current signals recorded on at least two tracks. Signals read from two tracks on a skew alignment test tape are compared for synchronism by simultaneous observation on an oscilloscope, as described, for example, in H. R. Scull U.S. Pat. No. 4,062,047, granted Dec. 6, 1977. The phase difference between two test signals is a measure of the skew misalignment. A different test tape having alternating current signals extending across different widths is often used as described in L judmirsky et al. U.S. Pat. No. 3,852,815, granted Dec. 3, 1974, for the determination of vertical alignment.
With single track data recorders, i.e., one track for each direction of tape travel, conventional methods of testing and alignment require up and down movement of the head with one test tape for vertical position followed by an angular, rocking movement of the head with another test tape for skew position.
It is an object of this invention to provide a single test tape for inspection and alignment of magnetic tape heads in data recorders with respect to both vertical and skew positions simultaneously and to eliminate the vagaries associated with prior methods which require movement of the head. The required inspection is rapid enough, moreover, for use in a production environment.